Views from airliner windows tend to appear flattened (i.e., the view lacks binocular effect). The Rocky Mountains even appear modest in scale as seen from an airliner. This is because depth perception is lost primarily because of the distance to the ground. At night, it is even more difficult to see from an airliner window due to darkness. Current external camera views from airplanes suffer from the same flattened appearance due to monocular vision combined with reduced resolution compared to the naked eye and the distance to the ground.
Another type of view from an airplane is aerial photography for documenting geography. The view when documenting geography aerially is typically from directly overhead. Sometimes “stereo pairs” of images of a single area are made by taking photographs from different passes by the airplane over the same geography. The first pass might be an overhead image while the second pass is laterally offset from the first pass, providing an overlap for a portion of the initial image. This pair of images may be used later in a special viewer to enable a technician to discern the altitude of objects and the altitude contour lines of the terrain. Standard three-dimensional aerial photography techniques, such as the two pass approach just described, have a substantial time delay between the first and second shots of a subject. This means that the subject must be stationary for the three-dimensional representation to be accurate and there is no means during the flight or afterwards to adjust the interpupillary distance (except by adjustment of the second flight path).
Another type of view from an airplane is radar, such as military surveillance or “recreational” viewing of geography. Synthetic aperture radar is used in surveillance airplanes. This system records radar returned over a period of time corresponding to a spatial distance. This effectively increases the physical size of the radar antenna (its “aperture”), hence the name “synthetic aperture.” The signals are highly processed to obtain the enhanced resolution that accompanies a larger aperture. However, radar produces a view of geography that is not natural to a typical viewer—it is not like a photograph at all nor is it a binocular view.
A different type of viewer is Google's “Google Maps,” in particular its “Street View.” Google Maps is a web-based application that provides a computer viewer with maps of the Earth in various overhead views. The Street View provides a melded, panoramic view of the geography from the street level, typically in 2-D, but with some available in three-dimensional. The three-dimensional images use red-cyan biased images that require viewing with red-cyan glasses. it is believed that these viewers may use a stereo-pair camera system. This type of system takes multiple still images from multiple cameras.
Existing stereo images are formed by the simultaneous use of two cameras, such as those filming techniques used for movies. The geometric distance between their lenses defines the three-dimensional effect that results. This distance is generally not adjustable and a relatively short maximum distance is constrained by physical considerations such as weight and bulk.